Wide band calibrated tuner and inductor for use therewith



Dec. .1.2, 1950 F. N. JACOB ET AL 2,533,810

WIDE BAND CALIBRATED TUNER AND INDUCTOR FDR USE THEREWITH Dec. 12, 1.950

Filed Augk. l5, 1949 MEGCYCL ES F. N;J WIDE BAND CALIBRA ACOB ET AL TED TUNER AND FOR USE'THEREWITH INDUCTOR 2 Sheets-Sheet 2y Patented Dec. 12, 1950 Mille Clim dustrxes'ncorp .tout and Lamar@ 'refus 4madam n1T orages; oiiagmfiln., afname'- Aisplication August 13, 1949, saigne. no ,ic

' Our inventionrelates t'o .anirnproved' tuner capahle `of #tuning Aa plurality of circuits overl -a'wide frequency band With'la/predete'rmnd frequencytuning movement characteristic and good tracking,- and an inductor for use therewith.

vIn -tuners `for television use -it is' necessary to cover two spaced-frequency bands, one Yband extending from approximately v5'1-mc. to about =85 mc; (channels 2 to 6 j) and the other band extending `from approximately 177 mc. `to about Z13-imc. (channels 'Z-to 13) [Since thisisa verywde f-requency spread, and-'thetuner -must cover this spread despite the constant circuit and capacitance-values, lit -is necessary tol-provide a' tuner wtha veryvviderange of varia-tion. Moreoven sincejth'e frequency spectrum intermediate the spaced bands contains no television stations, it is c lesirable to cover this freq'uency range with a relatively vsmall tuning movement. However,l since this frequency spectrum may contain other stations, such asFM stations, it is desirable that the "tuner cover this yspectrum so thatthese stations `may be tuned ifA desired.

Conventional tuners are incapableV of covering the wide televisionfrequency n range 'because the limitsv of `tuning are restricted. Ailior e; ample, a timer 0f the movable Core. type :reaches .its ma. mum frequency with"thacorewthdrawn and frequency thus' established' `placsisa maximum limit on the numberi turns: 'The .minimum.frge` guency is lxed ,by th indutance with the' ACore fully inserted andthe difference/as'. compared with the maximum frequency-is limited ,by ,th characteristics of available cormaterials. For these reasons it has .notheretoore been possible to cover the `full television 'frequency `,rangewith a single. tuning .clamant. A.further desirablecharacteristic of atuner for `television purposes ,is .that it cover .the desiv 'd frequencyrange withgoo'd calibratonand track;

ing despite manufacturing tolerances. It is therefore a general object-of the ypresent invention to v.provide an. improved tuner suitable fortelevision use.

l Another @object of the ,present 4,ini/ventionis' to provide 4an improved inductor Acapable,of Vcovering the full frequencyr range of ,thQtelevision channels. l

Further itisanobjectof therpresentfinvntion to lprovide ,an improved v,calibrated tuner capable of covering -the ,full Y. television -frequency 4bands with good accuracy.

Yet another object. of thepresent inventionisto ,ofcovering awde .ffreguenxcy .range-r and .adapted 2 s tabeuaubifatea atthe points irl-.the `tuning rn.

rtlierjit is anpbbiect of the present invention t pro 'de anximproved tuner-capable of tuning ity' of circuits in unison .over-@thev television* frequency bands vs/ith good accuracy and gpod tracking. i

'Qur vin-veiti'o,';furtl 1er resides -inu providing a tuner capable of tuning .over lthe'f/frequency .spectrurifiV intermediate-*theytwo televisionubands as Wil ash-the television bands themselves. flhe'noveljfea ureswhichwe ebelieve to bezchari ofour#inventionfare-.setlforth vwith-.parfinl the appended-claims.- Our invention itself," foweven jboth as teli-tsr vorganization vv,and inethodof Aoperat'icxn', can-Joesty be 1 understood :by rference to the followirig` descriptionv taken .in connection with theaccompanying4` drawings, in which:

VFigure' prse'nt invention;`

l'fd'gure 2' is aside elevational view Aof the struc- Ature ofFigure l; v 1 Y 'Figur A"3i-s aiment elevationalnviewof thestru'cf ture of=Figure l;

Y AFigure 4 is an axial cross-sectonal-.view.of an inductor constructed in; accord with the sprin- I"cip softhelpres'ent invention;

eures Lie-.3. there is srqw iferwardfaild r 1S spessi which tit @lines-an annular groove-,in .,h the. arr1ase2-p1at ,was smelly received. n nsulating: plate 2pc VA ci phenol fgrmaldshy fissi.

has a.

structe'diin 4accordancfl: -`with .the .principles .of the which is received in the elongated guide slot IIld of the top plate IIIc.

The slot Ild, coacting with the protuberance 2Gb, holds plate 26 against rotation and connes that plate to translational movement longitudinally of the shaft I2.` This movement is controlled by the cam mechanism described in further detail hereafter.

The shaft I2 carries the cam 22 in the region between carriage plate 2l! and front plate Ila. This cam is rigidly secured to the shaft I2 by the set screw 22a so that the cam rotates with the shaft. As shown, the cam 22 defines a spiralled surface 22h adapted to receive a cam follower.

The carriage is attached to the bracket 24 which carries the vertical roller 26. This roller has an enlarged portion 26a which rides on vthe rear face of the cam spiral 2217. The bracket 24 extends along the plate 28 as indicated in Figrure l and terminates in forwardly extending support 24a. Support 24a rockably carries the arm 21 which, as shown in Figure 1, extends to a point opposite roller 26. At its end, the arm 21 receives a roller 28 which is held to the arm by a suitable pin 28a.

The arm 21 is biased by spring 30, Figure 1, to hold the roller 28 against the forward surface of cam spiral 22o. Since the carriage plate 2li is free to move longitudinally to the shaft I2, this causes the carriage plate to follow by shifting movements the rotations of the shaft I2.

The cam 22 carries a series of pins 32. Each of these pins is threadedly received in the star plates 22e which is rigidly attached to the cam 22. Each pin extends rearwardly through appropriate openings in the cam 22 to a point on the rear face of the cam spiral 22h.

One pin 32 corresponds to each station channel desired to be tuned and rides against roller 26a when the tuner is adjusted to that station. Each pin can be individually adjusted to take up any departures in the shape of cam spiral 22h from the proper shape. These adjustments are made by suitable slots in the forward end of. each pin.

Vernier adjustments of the carriage plate 20 are achieved by rotation of the shaft I4. This shaft is threadedly held at portion I4a to the front plate I @a by the threaded collar 34. As

, the. shaft I4 is rotated, the front face` I4b is shifted relative to the front panel Ia and the entire assembly comprising cam 22, shaft I2, and carriage plate 23, is shifted against the bias of the. disk spring 3B. The latter spring bears against rear panel I0b and the washer IZa at the rear end of shaft I2 to hold the front end of shaft I2 (and hence the snap collar I5) snugly against the front face I4b of the shaft I4.

The shaft I2 is releasably held in any one of the station positions by the star wheel 22e, Figure 3, which is affixed to the cam 22. As shown, thisv wheel has a plurality of indentations, one corresponding to each station. An arm 38, Fgure 3, is rockably secured to the front plate lila by the pin 38a. This arm carries roller 4I), Figure 2, at its outer end. The arm 38 is biased by spring 43, Figure 1, to hold the wheel 40 against the periphery of wheel 22e and cause the shaft I2 to snap into the various positions corresponding to the station channels.

A plurality of inductors 42 are mounted on the rear panel Illb. Each of these inductors has a `cooperating tuning sleeve 44, Figure 2, which is adjustably held on the carriage plate 20 by coiled wire supports 46, each support being threadedly received in the portion 20a of the carriage plate 20. Each inductor 42 has a magrnetic core 60, Figure 4, positioned interiorly of lthe movable tuning sleeve 44.

From the foregoing description lt" will be evident that the tuner structure of Figures 1 to 3 adjustably positions the sleeves 44 relative to the inductors 42. The relative positions are determined by the rotation of the shaft I2, the setting of the Vernier shaft I4, the adjustment of the pins 32, and the settings of the individual threaded connections between each coiled wire 46 and the carriage plate 20.

The inductor In accordance with the present invention an improved inductor is provided for use in the tuner of Figures 1 to 3 or a similar tuner. The construction of this inductor is shown in enlarged view in Figures 4 and 5.

As shown in Figures 4 and 5, the tuner has longitudinal sleeve or tube 48 of a phenolformaldehyde condensation product or other low loss insulating material. This tube is supported from the back panel Ib by the strip 58 of in sulating material which snugly receives the projecting portion of the insert 52. Insert 52 in turn is snugly received by sleeve 48 to hold that sleeve in position. As shown in Figure 3, the strip50 extends across the panel IIlb and holds a plurality of inductors. It is secured to the panel by any suitable means, such as rivets.

A strip of copper or similar low loss conducting material 54 is wrapped spirally about the tube 48. This strip is secured by the inserts 56,

Figure 5, which are snugly held between the end sleeves 58 and the sleeve 48. Preferably the strip 54 is attached to the inserts 56 by soldering.

The strip 54 extends away from the tube 48 adjacent the points of attachment to the inserts .y

A magnetic core 66 is mounted inside the tube'.

48 and the winding formed by the strip 54. This core is held in position by the coiled wire 62 which defines a threaded outer surface and threadedly received in the insert 52. The core 60 is formed over the forward end of the wire 62."

The core 6D and the sleeve 48 define an annular fr space to receive the low loss conducting sleeve V 44. The effective inductance of the coil defined'. by strip 62 is varied by shifting this sleeve into* and out of the coil. The pitch of the spiral defined by the strip 54 is varied along the length of the tube 48. Consequently, as the sleeve 44 encircles increased portions of the core 60, the number of turns of the coil affected by a predetermined sleeve movement is varied. This varies the rate of inductance change with tuning movement.

Preferably the pitch of the turns of the coil defined by strip 62 is varied' along the length off the coil and the pitch of the cam spiral 22h `is varied along the length of the cam so that the station channels desired to be tuned are spaced by substantially equal rotations of the shaft I2.

In accordance with the present invention the pitch of the winding formed by conductor 54 is varied to cause a relatively small tuning movement near the center of the range of tuning sleeve travel to cover the relatively large frequency range between the two spaced television frequency bands. This is accomplished by winding the strip 54 to form two spaced portions 82 and masacre;

. thentunlng frequency to `177 `inc. .as shown in .Maurel-36;,

Afterf the tuninewsleeverhas passed. the turns B6.. 'Z'.The'sewturnscorrespond to theghighfrequencyfggend off-the tuningrange.- and.. the' high frequency. televisionfband This handV covers .the frequency ran'ge 'from 177. me. to.. 213.11m. (channe1S'|\-1toi1I3),. Asi-,Shown in.v Figure v6, theffreouencyfchan'ge with tuning movement in f. this region.` similar..-to .that s in the; iow Y. frequency :With =-somer core .materials it isv .desir-able to divide thel Icore-lin intotwo sections, one corre- 'spending tothe vlow frequency bandand the other corresponelingv to .ther-.high frequency band, .The former section, ,60a,is placed under the turns 62 and 'is made of .core vmaterial having V.good permeabilityfeyen-.sif the. .material Yis unsatisfactory for use in thieu` 'high .frequency sband. due Wto. large energyqlosses. ,Since this Imaterialsis ineffective at the frequencies'becau se .of, the. shielding action of sleeve 44, its poor characteristics .la-'t thesefrequencies do notinuence .thefhigh frequenc erformance of..thetiuiitlV 'Eheghigh frequency portionfof the. -core, Sb.. is. made of a. materialhaving good.. characteristics in the high frequency. fhancl,y even. if 'this requires aI reduction` yin permeability.

Figure- .7 showsthe schematicdiagramfof a tuned radio frequ encyv amplifier utilizing the. in-

ductoroafFigures Land @and the tunenofliigures lote; 3 I 'As .-shown,..anf .inductor Y M2 vis .connected in-isei with trimmer .capacitor lbetween .the pontrolelectrode and :the cathode of .electron tube .-.In'ductor 1.42. defines aresonant/circuit in conjunction-,with"trimmer c`apacitcr"`l'0. Sinii.- larlyptheinductor. 4Mila is Aconnected in series -withunidirectional voltage source. 'i2 .between the `.anode and ..cathode of electron tube 88. In- .ducto-rVv 142 d -deiines va resonant. circuit Yin conjunc- -withthel-trmme capacitor '13. .Input volt- .age, is. fed to the. amplifier through coupling capactorfl'l and output voltag'e'is taken'from camminare. l

` 'Idu'ctor's |12 and '1nafliigure'represeut two ofthe inductors 42 on the tuner of Figures 1 to"3. -Whenthe 'shaft l2 is rotated; Vthe lmovable sleeves of these-'tuners are rrovedfinunison to tune 'the v'cir :its lo Figure "7 .in tracked relationship. vrJisuesc bed in Donald Ri De'rar patentl appu- 'c at'io'ri." Serial No. '421607 entitled "Sleeve' Tuner?,

- n'filed'. August f5, '1948; the use of the movable 'sleeve vare adjusted.

6 from .the desired-istationthat `theffvernier. mecheanism is incapable of tuning the desired. station.. Moreover, f the several circuits must A.maintain theirzaligned or tracking conditions duringtun ing. However, apractical manufacturing to1er-` ances must be allowed for .in the` various portions oftheis'tructure-tc pern'lit-manufactureat reasonable .roost '.These two conflicting requirements become.fvery1.severe inthe case -of a tuner intended to:.fcoverzfalwide frequency'range,parf

ticularly. ifthe frequency rangeencompasses two bands-,1isinceigdeviations. from :the` designv characteristics of any. of thexcomponents vcause progressive.. deviations 'from the intended calibration curvewith the. consequent loss of calibration-.and departurezfrom the tracked condition.

In accordance with the presentzfinventiomme manufacturingptolerances for the component parts :are accommodated by a three point calibration made possible by the use Aof the movable cores,. the movablesleeves, and the variabletrimmer-capacitors. By adjusting these elements to secure. exact calibration atselected. critical frequen'cies, thefeffectof manufacturing tolerances on .the over-al1 calibration .curve and .tracking characteristic is brought within permissible limits.

.In'calihrating the tuningsystem, the carriage piateil is advanced by rotation of shaft I2 until the sleeves-x44 .are ful-ly inserted. This isthe position'corresponding to the highest vfrequency vcha'hiueLjnarnc1y213mc. The trimmer capacitors for the various inductors-.are.then .adjusted until x each is` tuned. to this frequency.

Since the'magnetic cores @care fullyencircledby the sleeves Min this position, the exact ad- `justin-ent ofthe coresdoes not influence vthe setting of the'trimmer capacitors. Moreover, the `resonant frequency is relatively insensitive itc/.movements of the tuni-ngsleeves `when the sleeves are fully inserted and the positionsof the tuning sleeves are therefore not critical.

The shaft l2 `is then rotated to the position correspondingto the lowest frequency channel, namely 57 rnc. vWith this adjustment, the sleeves Miiare fully withdrawnand the resonant frequency .is largely determined by the exact positions yofv the coresA 60. Each inductance .is tuned fby rotation of the :support 63 to adjustthe positionof the corresponding core 60 to tune vthe 57 rnc. channel.

Since the tuning is :relativelyl insensitive to sleeve .movement .at the low. frequency endof the tuning range., the exact sleeve position is .:not critical in setting the positions of the cores.` The trimmers are` left inthe position of adjustment fixed by the initial high frequency calibration when the position of the corresponding cores Following the foregoing adjustments,the shaft I2 is rotated tothe lposition.corresponding v,to channel 6 (.85 ma). At this channel the tuningr .-sleevegposition is vmost critical andthe greatest frequency change results from a giventuning movement. The springsupport 46 is rotated with the shaft l2fset Lforthe channel 6 position until the inductor is tunedI to the 85 megacy-cle fresquency, thus providing ,an exact Ycalibration of `the inductor at this critical position.

:Since the tuner is almost as sensitive tosleeve -rmovementeat 'channel l (177 mcg), the calibrationmay,4 if desired, be --made at 'this frequency.

:After the :unithas been calibrated-Lat thefminimum, maximum, and. .intermediatetuning positions.' the. foregoing asteps *are repeated-` to coni?,

pensate for any interrelationship between the tuning settings.

` We have found that the tuner of the present invention is easily calibrated to accommodate generous manufacturing tolerances and that once the foregoing calibration is made, the calibration of each production tuner displays no substantial departure from the standard calibration curve. Moreover, the various tuned circuits retain their tracked condition over the entire tuning range. A radio frequency transformer having features in common with the tunerand inductance of the present invention is described and claimed in a copending application entitled Radio Fre- -quency Transformer, S. N. 114,294, filed Septem- .ber T, 1949, assigned to the same assignee as the present invention.

The frequency spectrum intermediate the ,spaced television bands may include stations of interest, such as frequency modulated broadcast stations. v'If it is desired to tune these stations :as well as the television stations, the tuner of .Figures l, 2, and 3 may be provided with mechanical elements operable to move the carriage over the range of movement associated with these frequencies.

While we have shown and described a specific embodiment of our invention, it will, of course, ibeunderstood that we do not wish to be limited thereto and that by the appended claims we intend to cover all modifications and alternative constructions as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

`l. A multicircuit tuner operable to tune over spaced frequency bands upon predetermined movements of a tuning member, said tuner comprising in combination, a helical inductance coil corresponding to each circuit and having spaced portions of relatively low turn density and an intermediate portion of relatively great turn density, an adjustable capacitor defining a resonant circuit in conjunction with each coil, amagnetic core disposed within each of said coils and adjustably mounted relative thereto to calibrate said coils at the low frequency end of the tuning range, and a conductive tuning sleeve for each of said coils adapted to telescope over said core and adjustably mounted on the tuning member to calibrate said coils at a frequency intermedi ate the low and high tuning frequencies. 2. An inductor operable toltune a resonant circuit over spaced frequency bands upon prede termined movements of a tuning member, said inductor comprising in combination, a helical coil having spaced portions of relatively low turn density and an intermediate portion of relatively great turn density, a magnetic core disposed within said coil and adjustably mounted independently of the tuning member to calibrate the low frequencyl end of the tuning range, and a conductive tuning sleeve adapted to telescope over said core and within the coil and adj u-stably mounted on the tuning member to calibrate the inductor at a frequency intermediate the low and high tuning frequencies.

3. An inductorsuitable for tuning a resonant circuit over two spaced frequency bands comprising in combination, a tuning member, a helical coil having spaced portions of relatively low turn density and an intermediate portion of relatively great turn density, a magnetic core disposed within said coil and adjustably mounted independently of the tuning member to calibrate the low frequency end of the tuning range and conductive Atuning sleeve mounted on the tuning" member adapted to telescope over said core and within the coil.

1.1.. A tuning unit for a radio receiver ofthe type wherein a plurality of circuits are tuned inunison by movements of a tuning member, said unit comprising a plurality of helical windings, adjustable capacitors connected to said windings todeiine resonant circuits in conjunction therewith, magnetic cores adjustably positioned within said windings, and conducting sleeves adapted to encompass more or less of said cores Awith movements of said tuning member and adjust' ably held on said tuning member.

5. A multi'circuit tuner operable to tune-over spaced frequency bands upon predetermined movements of a tuning member, said tuner comprising in combination, a helical inductance coll corresponding to each circuit and having spaced portions of relatively low turndensity and 'an intermediate portion of relatively great turn den'- sity, a magnetic core disposed within each of said coils and adjustably mounted relative theretoV to calibrate said :coils at the low frequency end of the tuning range, a capacitor connected in cir; cuit with each of said coils to denne a resonant circuit in conjunction therewith and variable to calibrate said coils at the high frequency end of the tuning range, and a. conductive tuning sleeve for each of said coils adapted to telescopeoveni the corresponding core and adjustably mounted on the tuning member to calibrate said coils at a frequency intermediate the low and high tuning frequencies. i f

6. An inductor operable to tune over spaced frequency bands upon predetermined movements of a tuning member, said inductor comprising in combination, a helical coil having spaced portions of relatively low turn density and an intermediate portion of relatively great turn density, a magneti-c core disposed within said coil mounted independently of the tuning member, and a low loss tuning sleeve adapted to telescope over said core and within the coil to tune said inductor.

7. An inductor tunable over a relatively wide frequency band and capable of being calibrated at a plurality of points therein comprising in combination, a winding defining an inductance, a magnetic core member operably associated with the winding and adjustably mounted relative thereto, a member movable independently of the core and the winding, and a shield movable in unison .vwith the member adjustably positioned relative thereto and operative to extend between the core and the coil to shield the core from the coil in accord with the movements of the mem-'- ber.

8. An inductor tunable over a relatively wide frequency band and capable of being calibrated at a plurality of points therein comprising in combination, a winding defining an inductance, a magnetic core member operably associatedwith the winding and adjustably mounted relative thereto, a supporting member movable independently of the core and the winding, means to move the supporting member over apredetermincd range of movement for station selection, anda shield carried by the supporting member adjust ably positioned relative thereto and operative to shield the core from the coil in accord with the Amovements of the supporting member.

at a plurality of points therein comprising in coin--A 2,533,810 9 10 bnation, a helical coil, a magnetic core member REFERENCES CITED disposed within the coil and supported relatively thereto by means dei-ming a threaded connection for adjustment of the core relative to the coil,

The following references are of record in the file of this patent:

a supporting member movable independently of 5 UNITED STATES PATENTS the coil and the core, a conducting sleeve adapted Number Name Date to be received in the annular space between the 2,259,250 Jacob Oct. 14, 1941 core and coil, and means dening a threaded con- 2,338,134 sands Jan. 4, 1944 nection adjustably supporting the sleeve from 2,363,101 Van Der Heem Nov, 21, 1944 the supporting member. l0 2,477,979 Hadley Aug. 2, 1949 FREDERICK N. JACOB. EARL R. STOUT. LEONARD IVIILLER. 

